There are many emerging uses for gas sparged hydrocyclones in the treating of fluent materials in general, particularly liquid slurries and liquids.
In a gas sparged hydrocyclone, such as shown in U.S. Pat. Nos. 4,279,743, 4,399,027, and 4,838,434, the fluent material is introduced into a hollow body to establish a vortex, and gas is sparged through a porous surrounding wall into the vortex. Gas, and elements carried thereby, are withdrawn from the center top portion of the vortex, while the fluent material is withdrawn from a bottom portion of the vortex. While the hydrocyclones illustrated in the above-identified patents are used solely for flotation, it has recently been established that the hydrocyclones are useful for many other processes, such as shown in co-pending application Ser. No. 07/573,975 filed Aug. 28, 1990, entitled "Gas Sparged Centrifugal Separation and/or Mixing", including effecting chemical treatment of solids in a slurry with a chemically reactive gas, scrubbing flue gases, chemically reacting a liquid with a gas, stripping a strippable component from a liquid utilizing a stripping gas, and absorbing a gas within an absorbable component in an absorbent liquid.
The present invention relates to a hydrocyclone, and a method of treating fluent material utilizing a hydrocyclone, to improve the versatility of existing gas sparged hydrocyclones, and in some circumstances the efficiency thereof.
According to one aspect of the present invention, a hydrocyclone is provided that has--in addition to the conventional components of a hollow body, inlet at a first end for fluent material establishing a first vortex within the hollow body, fluid withdrawing means from the first end (e.g. top) of the vortex, a porous surface of revolution disposed within the hollow body wall, and a plenum between the body wall and the porous surface of revolution--means for establishing further vortex action in a volume between the porous surface of revolution and the withdrawal means for fluent material. The second vortex is established by a conical bottom section of the hollow body extending from below the porous surface of revolution to the fluent material withdrawing means.
Desirably a shroud--such as a conical shroud --having a circumferential periphery is disposed above the conical bottom section, and intensifies the second vortex action. A plurality of legs, or like mounting means, mount the shroud so that fluent material may pass between the circumferential periphery of the shroud and the porous surface of revolution, but the mounting means does not disrupt flow patterns. A central axially extending gas passage is formed in the shroud allowing passage of gas separated in the conical bottom section to flow to the gas withdrawal means at the top of the first vortex. Some fluent material--particularly a heavier particle fractions of a slurry--may be tangentially withdrawn from the conical bottom section at a part thereof adjacent the porous surface of revolution.
According to another aspect of the present invention, a hydrocyclone is provided having--in addition to conventional components--a wall dividing the plenum into at least first and second axially spaced portions. A liquid may be introduced into one of the plenum portions, and the gas into the other, the liquid being introduced so that it has a pressure drop across the plenum so that gas therein (the liquid may be saturated with gas) will be released in small bubble form.
According to another aspect of the present invention, a method of acting upon fluent material is provided which comprises the following steps: (a) Introducing the fluent material into a first end of a first vortex. (b) Introducing fluid from exteriorly of the vortex into contact with the fluent material in the first vortex. (c) Removing some fluid from the first end of the first vortex. (d) After step (b), subjecting the fluent material to a second vortex action. And, (e) removing fluent material from the second end of the second vortex. There preferably is the step (f) of removing a portion of the fluent material (a slurry with heavy particles therein) tangentially from the first portion of the second vortex. There may be the still further step (g) of shrouding the central axis of the second vortex while allowing axial (e.g. upward) passage of gas from the central vortex to be withdrawn as fluid in step (c).
According to another aspect of the present invention, a method of treating fluent material is provided which comprises the following steps: (a) Introducing fluent material into a fluent material vortex within the porous surface of revolution. (b) From exteriorly of the vortex, introducing liquid through the porous wall into the vortex so that the liquid experiences a pressure drop as it passes through the porous wall. (c) Removing gas from the first end of the vortex. And, (d) removing treated fluent material from a second end of the vortex, opposite the first end.
Utilizing the apparatus and processes as set forth above, a wider variety of treatments can be given to fluent material, and/or the efficiency of existing treatments (such as flotation) may be enhanced.
It is the primary object of the present invention to provide hydrocyclones and procedures with improved versatility and/or efficiency compared to conventional gas sparged hydrocyclones and procedures utilizing the same. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.